Companies are interested in allowing insertion or replacement of advertisements within existing image/video/film sequences. A human operator can identify areas of interest that allow carrying advertisements—such as plain walls of buildings. Such areas need to be tracked along the image sequence by means of motion estimation and tracking processing. As an alternative, areas of interest can be identified automatically or semi-automatically, provided the necessary technology is available. One approach would be to place, in a single image frame F, markers (e.g. small squares or rectangles or even points) at positions in and/or around areas of interest that seem appropriate for motion estimation and tracking along the video sequence. The corresponding image content or rather (center) pixel, found by motion estimation, feature point tracking or other methods in the next frame F+1, is used as a starting point for estimating the motion from frame F+1 to frame F+2, etc. In case of integer pixel motion estimation, there may result a spatial deviation from the precise motion in the scene, which deviation may accumulate over time and result in misplaced points. For good-quality point tracking, sub-pel resolution is required in the motion estimation. Typically, integer-pel motion estimation—by hierarchical motion estimation or other methods—is carried out first, followed by sub-pel refinement stages.